Cells to Organs Flashcards
What are tissues?
Tissues contain specialized cells that are similar in structure and perform a common function.
What is homeostasis?
The ability of the body to maintain a constant internal environment regardless of the changes occurring outside the body.
What are the different kinds of tissues found in the body?
- Epithelial
- Connective
- Muscle
- Nervous
Describe epithelial tissue.
- Widespread in the body.
- Forms the covering of all body surfaces.
- Lines body cavities and the surfaces of hollow organs.
- Forms the major tissue in glands.
- Avascular; receives nutrients from basement membrane beneath.
What are the characteristics of basement membrane?
- Contains fibers like collagen.
- Semipermeable
What are the functions of epithelial cells?
- Secretion
- Absorption
- Excretion
- Filtration
- Diffusion
- Protection
- Sensory Reception
Why are epithelial cells said to be polar?
Because they have an apical and a basal end.
What are the different kinds of epithelial tissues based on the number of layers?
- Simple- Single layer
- Stratified- Several layers
What is the difference in function of simple and stratified tissues?
- Simple tissues are found where diffusion takes place.
- Stratified tissues are found where resistance against mechanical and chemical stress is required.
What are the different kinds of epithelial tissues found on the basis of location?
- Membranous- Forms the lining of organs and body surfaces
- Glandular- Forms endocrine and exocrine glands
What are the different kinds of epithelial tissues based on cells?
- Squamous
- Cuboidal
- Columnar
- Transitional- Squamous cells on top, cuboidal beneath
What are the characteristics of squamous tissues?
Simple squamous:
1. Elastic in nature and very thin.
2. Found in air sacs of lungs and blood capillaries.
3. Transfer in waste, nutrients and gases.
Stratified squamous:
1. Forms the layers of skin, mouth and vagina.
2. Protects against abrasion, infection and drying out.
3. Replenishes fast.
What are the characteristics of cuboidal tissues?
Simple cuboidal:
1. Found in glands and kidney tubules.
2. Secretes and reabsorbs water and small molecules.
Stratified cuboidal:
1. Lines ducts of sweat glands.
2. Secretes water and ions.
What are the characteristics of columnar tissues?
Simple columnar:
1. Lines most of the digestive organs.
2. Secretes mucus.
3. Absorbs nutrients.
Stratified/ pseudostratified:
1. Lines epididymis, mammary glands, larynx.
2. Secretes mucus.
Why are pseudostratified columnar tissues named so?
- The cells forming them are incomplete.
- The illusion is given by the positioning of the nuclei which are not leveled properly.
What are the different types of cell junctions?
- Tight junctions- Prevent leaks
- Gap junctions- Connect the cytoplasm of different cells
- Adhering junctions- Cement the cells together.
What are the characteristics of connective tissues?
- Found throughout the body.
- Provides framework and support to the organs and the body.
- Multiply less quickly than epithelial cells.
- Most are provided with a blood supply but not all.
What are the functions of connective tissues?
- Binds organ structures together.
- Provides framework and support of organs and body.
- Transfer of substances.
- Repairs tissue damage
- Stores fat.
- Protects against diseases.
What is common in all the connective tissues?
- They originate from mesenchyme- a loose, fluid embryonic tissue.
- They have extracellular material.
- They have varying levels of vascularity.
What are the different components of a connective tissue?
Connective tissues contain cells and extracellular material.
The different cells in the tissue are macrophages, mast cells and fibroblasts.
Extracellular material consists of ground substance and fibers.
The ground substance includes starch and protein molecules, and an anchoring system.
The fibers present are collagen, elastic and reticular.
What is the anchoring system present in the ground substance of extracellular material in a connective tissue?
The anchoring system is provided by proteoglycans from which glycosaminoglycans emerge as bristles to hold water molecules.
What are the different types of connective tissues?
Connective tissue proper and specialized connective tissue.
What are the types of connective tissue proper?
Loose connective tissue and dense connective tissue.
Loose connective tissue includes areolar, reticular and adipose tissue.
Dense connective tissue includes regular, irregular and elastic.
What are the characteristics of loose connective tissues?
- Matrix> Fibers
- Found under skin and most epithelia.
- Provides support and elasticity.
